Wildfire in California, May 1 to 6, 2021

Area Forecast Discussion
National Weather Service San Diego CA
139 PM PDT Sat May 1 2021

.SYNOPSIS...
A deepening trough over the western U.S. will trigger cooler
temperatures across the region, along with gusty winds across the
mountains and deserts this weekend. A ridge of high pressure will
take over by the early and middle parts of next week bringing a
warming trend with more dry conditions. Another trough to the
north will bring some cooler weather by later next week.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

.SHORT TERM...(Today through Tuesday)...
High clouds will continue to stream over the region today with
another hot day across the deserts and much cooler for the coast
and valleys. Winds are starting to pick up at this hour, where
gusts over 35 MPH are occurring along the 10 in the San Gorgonio
Pass. A trough draped over the Pacific Northwest is contributing
to these cooler and windier conditions. This feature will continue
to deepen across the western CONUS this weekend and make an aim
for the Desert Southwest. Latest model guidance continues to show
gusty west winds across much of the eastern/northern parts of the
mountains into the deserts this afternoon, continuing through
Sunday evening. Highest winds will occur this evening into early
Sunday morning with gusts over 55 MPH in some spots. Santa Ana
winds will make a brief appearance Monday morning on the backside
of the outgoing trough. The San Bernardino, Riverside and Santa
Ana mountains may gust over 35 MPH at times. This will be
accompanied by low relative humidity values, so near critical fire
weather conditions are expected.

The marine layer will build this weekend, prompting low clouds to
push onto the coast and fill parts of the Inland Empire each night
and morning over the next few days. Sunday will be the coolest day
of the week with temperatures up to 10 degrees below average. A
ridge over the eastern Pacific will slowly progress into Southern
California early next week bringing subtle rises in temperatures
and continued dry weather.

&&

.LONG TERM...(Wednesday through Friday)...
The ridge of high pressure will amplify into Wednesday, where the
hottest day of the week will be felt. Temperatures will be up to
15 degrees above average. Upper 80s and low 90s look likely across
inland valleys into the high desert, with temperatures near the
century mark near Palm Springs. Cluster analysis paints a picture
of another trough coming into the Pacific Northwest later in the
work week, which will provide a bit of cooling across our region.

&&

.AVIATION...
012030Z...Coast/Valleys...Low CIGS will return quickly this evening,
surging inland beginning 00-02Z Sun, with bases of 1000-1500 ft MSL.
Clouds will extend well into valleys, including the Inland Empire,
through 12Z Sun, with some lifting of cloud bases likely through the
night. Vis restrictions will be confined to higher coastal terrain
obscured by clouds, and possibly some of the valley locations (e.g.
KRNM).

Mountains/Deserts...VFR conditions will prevail through Saturday
night, with extensive high cloud coverage likely above 25000 ft.
Surface winds will increase along mountain ridgetops, through passes
and into portions of the deserts this afternoon, continuing through
the evening. Sustained winds of up to 30 kts, with gusts up to 50
kts, can be expected for the windier areas, leading to LLWS over and
east of the mountains. Coachella Valley terminals will see gusts to
around 30 kts late this afternoon through this evening.

&&

.MARINE...
No hazardous marine weather is expected through Wednesday except for
occasional gusts around 20 knots near San Clemente Island this
afternoon and evening and again Sunday afternoon and evening.

&&

.BEACHES...
South swells up to 3 feet with period 16-17 seconds will produce
elevated surf, strong rip currents and dangerous swimming conditions
at some beaches this weekend. Surf will build this afternoon, peak
Sunday and subside Monday. This southerly swell will lead to
breaking waves of 4-6 ft, with local sets to 7 ft at favored beaches
in Orange County and far northern San Diego County. Short period
wind-driven WNW swell on Sunday may drive up the surf somewhat in
southern San Diego County, with sets to 6 feet at times under messy
conditions. Otherwise, surf will generally remain in the 3-5 ft
range for most San Diego County beaches.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until 11 PM PDT Sunday for Coachella Valley-
     Riverside County Mountains-San Diego County Deserts-San
     Diego County Mountains-San Gorgonio Pass Near Banning.

     Wind Advisory until 7 PM PDT Sunday for Apple and Lucerne
     Valleys-San Bernardino County Mountains.

     Beach Hazards Statement through Sunday evening for Orange County
     Coastal Areas.

PZ...NONE.
&&

PUBLIC...APR
AVIATION/MARINE/BEACHES...Brotherton